There are various material transport vehicles and trailers used to transport different loads such as soil, mulch, sand, gravel, screening materials, and other aggregates, organics such as mulch, feedstuffs for livestock, and agricultural products. These include dump trucks, slinger trucks, live bottom trucks, and live bottom trailers.
Traditional live bottom trailers generally have larger capacities than dump trucks and slinger trucks. Available live bottom trailers provide load capacities from 25 cubic yards (19.11 cubic meters) to as high as 50 cubic yards (38.23 cubic meters). Live bottom trailers have substantially horizontal hopper body bottoms. Typically, one or more tailgate doors of the hopper body open and an internal conveyor disposed at the bottom the trailer/hopper body discharges its load out the rear of the hopper body onto the ground behind the trailer. Unlike a dump truck, a live bottom trailer is not hoisted or vertically elevated when discharging material from the rear of the trailer.
Most live bottom trailers do not use throw conveyor systems because their hopper body is too low to provide a throw conveyor with adequate clearance from the ground. Some attempts have been made to include a throw conveyor with a live bottom trailer to discharge the material somewhat further. Because of the lower ground clearance of a live bottom trailer a throw conveyor cannot be easily configured to move to a stored position beside the hopper. Accordingly, throw conveyors have been configured to move to a vertical stored position adjacent the trailer's rear discharge doors. This storage position limits the length of the throw conveyor which in turn limits material discharge distances. Accordingly, the use of live bottom trailers is generally limited to readily accessible site locations and uses which do not require distant, directional discharge of material.
Slinger trucks are used to directionally discharge material greater distances. A traditional slinger truck has a hopper like body with an internal conveyor along the length of the hopper bottom and an external throw conveyor for receiving discharging material from the internal conveyor and projecting the material significant distances to desired throw or drop locations. The throw conveyor typically pivots from a travel storage position beside the hopper body to an end discharge position in alignment with the internal conveyor. The throw conveyor can move horizontally and vertically to direct the discharging material. The bottom of the hopper body of a slinger truck is configured differently than a traditional live bottom trailer. The hopper body has an inclined bottom wherein the hopper bottom is lowest at the front end (closest the vehicle cab) and highest at the discharge end. This inclined configuration is required so that the external throw conveyor can be pivoted and positioned under the discharge end of the internal conveyor at optimum angles for distant discharge of the material. The hopper body of a slinger does not elevate vertically in the manner of a dump truck. Whilst a slinger truck can discharge material directionally and for greater distances than live bottom trailers, the inclined hopper body limits the load capacity of slinger truck and raises the center of gravity of the load. A higher centre of gravity may cause instability of a loaded truck. Different slinger truck hopper body lengths provide load capacities from about 18 cubic yards (13.76 cubic meters) to about 22 cubic yards (16.82 cubic meters).
It is desirable to have a vehicle with the versatility of delivering a large payload like a live bottom trailer and with the capability of discharging the payload like a slinger truck.
It is desirable to bring the load mass effective height of a live bottom hopper body closer to the ground surface whilst also increasing the volume of the hopper body. It is also desirable to lower the overall height of the unit to allow access to site areas that are traditionally more difficult to get to by slinger trucks and to be able to unload in the same time and manner as a traditional slinger truck using a throw conveyor.
It is desirable to maintain a maximum amount of ground clearance for a throw conveyor due to the nature of the locations where material is offloaded. Sufficient ground clearance is required to discharge and direct the offloaded material substantial distances. It may also be desirable to use standard configurations of throw conveyors.
Some material such as top-soil tends to compact or clump in a hopper body and adhere to the hopper body during transport. In such instances, discharging the material quickly and completely becomes challenging because during the discharge operation the material does not easily move to the hopper bottom onto the internal conveyor. Known metering beams utilize hydraulic cylinders with pulley's and cable to elevate and lower the beam. It is desirable to have a discharge system that has the capability of discharging large loads for all types of materials and to simplify the operation of metering beams.